The format of this field when previously filled in by hand is a follows: MH 7 PW 2 BF 1 which would represent Hard Maple 70%, White Pine 20% and Balsam Fir 10% for a total of 100%.
There are 30 different tree species that can be represented in this description but most times only 4 to 8 species will occur in an assessment area and the maximum number that will occur in this Species_Composition field will be 10 (100%). The values in the text field also have to show from largest to smallest.
Use a table called, say, TreesInObservation, where each record is a count of a tree species in an assessment, and thus would be a child table to an Assessment (?) table – at any rate, the table where the hand-filled field now resides.
Storing your figures this way allows you to create a report layout, use portal filters, perform SQL magic and lots of other goodness (even re-creating your old field) that with a text list would be next to impossible to achieve.
Try working along the lines of
AssessmentArea --< Assessment --< SpeciesInAssesssment (speciesID, count) >-- Species
MH 7 PW 2 BF 1
would become 3 records with fields and values like
assessmentID: 6 , speciesID: x, count: 7
assessmentID: 6 , speciesID: y, count: 2
assessmentID: 6 , speciesID: z, count: 1
where assessmentID denotes the parent table, and x, y, z correspond to the primary IDs of the records with the code MH, PW and BF, respectively, in a Species table.
You can display these records in a portal, list them in a report, calculate them into a text field etc.
I have read a bit about arrays and I am wondering if this would be the way to approach it?
FilkeMaker is (first and foremost) a database, not a programming language/environment; arrays (or their Filemaker equivalents – lists and repeating field) are mostly used for scripting and UI purposes, i.e. in a temporary manner, not for persistent data storage.
I might suggest that you set up a database for the collection of data using the iPad and using three fields: area_name; species; count. The person in the field can walk around the area, use a dropdown list of species and enter a count of trees in that particular area. He can then mave to another area, select this area by name (or give it a name) and do the same again.
The collected data or, the historical data can then be displayed in a table format. Down the left side use a list of the sample areas by name and across the top list the species. Then use summary fields to count the numbers of each species and their respective percentages of the total. Finally, display this information in the table format I descrided.
Took your suggestions and they were very helpful. Thank you again.